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1 – 10 of over 3000
Article
Publication date: 9 October 2023

Yuchen Xi, Qinying Wang, Xinyu Tan, Xingshou Zhang, Lijin Dong, Yuhui Song, Liyang Liu and Dezhi Zeng

The purpose of this work is to design the wire beam electrode (WBE) of P110 steel and study its corrosion behavior and mechanism under high temperature and pressure.

Abstract

Purpose

The purpose of this work is to design the wire beam electrode (WBE) of P110 steel and study its corrosion behavior and mechanism under high temperature and pressure.

Design/methodology/approach

Packaging materials of the new type P110 steel WBE and high pressure stable WBE structure were designed. A metallurgical microscope (XJP-3C) and scanning electron microscopy (EV0 MA15 Zeiss) with an energy dispersive spectrometer were used to analyze the microstructure and composition of the P110 steel. The electrochemical workstation (CS310, CorrTest Instrument Co., Ltd) with a WBE potential and current scanner was used to analyze the corrosion mechanism of P110 steel.

Findings

According to the analysis of Nyquist plots at different temperatures, the corrosion resistance of P110 steel decreases with the increase of temperature under atmospheric pressure. In addition, Rp of P110 steel under high pressure is maintained in the range of 200 ∼ 375 Ωcm2, while that under atmospheric pressure is maintained in the range of 20 ∼ 160 Ωcm2, indicating that the corrosion products on P110 steel under high pressure is denser, which improves the corrosion resistance of P110 steel to a certain extent.

Originality/value

The WBE applied in high temperature and pressure environment is in blank. This work designed and prepared a WBE of P110 steel for high temperature and pressure environment, and the corrosion mechanism of P110 steel was revealed by using the designed WBE.

Details

Anti-Corrosion Methods and Materials, vol. 70 no. 6
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 29 November 2021

Guangyuan Wu, Haitao Zhang, Junfeng Sun and Tengjiang Yu

In order to evaluate the rheological properties of asphalt more comprehensively and effectively, and to explore and discuss the practicability of relevant models in the evaluation…

Abstract

Purpose

In order to evaluate the rheological properties of asphalt more comprehensively and effectively, and to explore and discuss the practicability of relevant models in the evaluation of the rheological properties of asphalt.

Design/methodology/approach

Based on the rheological and viscoelastic theories, temperature scanning, frequency scanning and multiple stress creep recovery (MSCR) tests of different modified asphalt were carried out by dynamic shear rheometer (DSR) to obtain relevant viscoelastic parameters and evaluate the high temperature properties of different modified asphalt. Based on the time-temperature equivalence principle, the main curve was constructed to study the viscoelastic properties of asphalt in a wider frequency domain. The main curve was fitted with the CAM model, and the rheological properties of different modified asphalt were evaluated through the analysis of model parameters. The creep stiffness and creep velocity of different modified asphalt were obtained through the rheological test of bending beam (BBR), and the low-temperature performance of different modified asphalt was analyzed by using Burgers model to fit the creep compliance.

Findings

The results show that the high temperature rheological properties of several modified asphalt studied in the test are ranked from best to worst as follows: PE modified asphalt > SBS modified asphalt > SBR modified asphalt. Short-term aging can improve the high temperature performance of asphalt, and different types of modifiers can promote or inhibit this improvement effect. Based on BBR test and Burgers model fitting analysis, SBR modified asphalt has the best low temperature performance, followed by SBS modified asphalt, while PE modified asphalt has poor low temperature performance, so it is not suitable to be used as road material in low temperature area.

Originality/value

Combined with effective evaluation methods, the rheological properties of asphalt at different temperatures and angles were systematically evaluated, and the evolution of rheological properties of asphalt characterized by model parameters was further analyzed by advanced model simulation.

Details

Journal of Engineering, Design and Technology , vol. 21 no. 5
Type: Research Article
ISSN: 1726-0531

Keywords

Open Access
Article
Publication date: 13 October 2022

Junmei Zhang and Hongyi Li

This study aims to investigate whether temperature affects the product quality of exporters and whether the effect is non-linear. More specifically, whether the impact of high…

Abstract

Purpose

This study aims to investigate whether temperature affects the product quality of exporters and whether the effect is non-linear. More specifically, whether the impact of high temperatures differs from the impact of low temperatures, and whether different types of companies or industries are affected differently.

Design/methodology/approach

The paper uses detailed data covering all Chinese exporters from 2000 to 2016 to estimate the effects of temperature on the product quality of export firms. To clarify the relationship between them, the authors use a semi-parametric regression method, trying to test whether there is a non-linear relationship between temperature and the export quality of firms.

Findings

The increase in the number of high temperature days significantly reduces the quality of exported products, and this negative effect increases as the temperature rises. High temperature has the most significant negative impact on export quality for firms with low technical complexity, private firms and firms with no intermediate imports and located in historical hot cities. Product quality of both labor-intensive and capital-intensive firms will be affected by heat. High temperatures have the greatest negative impact on the export quality of newly entering products, followed by exiting products, with the least negative impact on persisting product.

Originality/value

To the best of the authors’ knowledge, this paper is the first to examine the impact of temperature on the quality of economic development. The findings of this paper again show that the potential economic impacts of global warming are huge. In addition to some potentially devastating impacts in the future, global warming is already causing imperceptible impacts in the present. Public and economic agents need to fully understand the possible adverse impacts of climate change and take corresponding adaptation measures to cope with global warming.

Details

International Journal of Climate Change Strategies and Management, vol. 15 no. 4
Type: Research Article
ISSN: 1756-8692

Keywords

Article
Publication date: 19 April 2023

Meixian Zhang, Hanbo Shi, Siyuan Ding and Lei Ma

The purpose of this paper is to study the influence of braking speed at –20 °C on the wear property of high-speed railway braking materials and the temperature also stress…

Abstract

Purpose

The purpose of this paper is to study the influence of braking speed at –20 °C on the wear property of high-speed railway braking materials and the temperature also stress analyses of brake disc friction surface.

Design/methodology/approach

Friction brake tester was used to simulate the wear test of high-speed railway braking materials at diverse braking speeds (2,100, 2,400, 2,700 and 3,000 rad/min) at –20 °C and the stress and temperature analyses of brake disc friction surface were carried out by COMSOL.

Findings

Compared with 20°C, there is initial stress of brake disc friction surface before brake starting; also, the maximum wear depth is larger at –20°C. Besides, at –20 °C, with the rising of braking speed, the graphite particles on the friction surface of brake pad significantly reduce. And scratches and cracks are formed on brake pad friction surface. Besides, the abrasive wear, adhesive wear and thermal cracks of brake disc friction surface are aggravated. Moreover, the maximal worn depth also increase. Meanwhile, the highest temperature and the maximum thermal stress of brake disc friction surface both raise. Furthermore, the temperature and thermal stress gradients at radial direction of brake disc friction surface aggrandize, which makes the thermal cracks on brake disc friction surface further exacerbated.

Research limitations/implications

In this paper, the wear property of the high-speed railway braking materials is studied by combining experiment and simulation. However, due to the low-speed traveling of high-speed railway was mainly studied in this paper, there may be no comprehensive simulation of the real running condition of high-speed railway. At the same time, the working condition of low-temperature environment cannot be completely simulated and controlled.

Practical implications

The research results of this paper provide a basic instruction for other researchers and also provide an important reference for relevant personnel to choose the braking speed of high-speed railway at –20 °C.

Social implications

The research of this paper provides a brick for the study of high-speed railway braking materials and also provides some references for the safe service of trains in low-temperature environment.

Originality/value

This paper studied the wear property and carried out the simulation analysis of braking materials at –20 °C at diverse braking speed. The research findings provide an important reference for the selection of braking speed of high-speed railway at –20 °C.

Details

Industrial Lubrication and Tribology, vol. 75 no. 4
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 4 November 2022

Ruizhe Wang, Runsheng Li, Guilan Wang, Mingbo Zhang, Jianwu Huang, Hang Lin and Haiou Zhang

Wire and arc additive manufacturing (WAAM) technology-based cold metal transfer (CMT) to produce large aluminum alloy parts has become more and more popular. In WAAM, wire is the…

Abstract

Purpose

Wire and arc additive manufacturing (WAAM) technology-based cold metal transfer (CMT) to produce large aluminum alloy parts has become more and more popular. In WAAM, wire is the only raw material. The purpose of this paper is to study the effect of wire composition on the microstructure and properties of the ZAlCu5MnCdVA alloy deposited by WAAM.

Design/methodology/approach

Two thin-walled ZAlCu5MnCdVA alloys with different wire compositions were prepared by WAAM. The copper contents were 4.7% (Al-4.7Cu) and 5.0% (Al-5.0Cu), respectively. The microstructure, element distribution and evolution of precipitated phases of the two samples were characterized and analyzed by optical microscopy, scanning electron microscopy and transmission electron microscopy. Hardness and tensile properties of samples were tested, and strengthening mechanism was analyzed in detail.

Findings

The results show that grain sizes of Al-4.7Cu and Al-5.0Cu are less than 40 μm. The average mass fraction of Cu in Al matrix and the number of nanometer scale θ'' and θ' phases are the main factors affecting the tensile properties of Al-Cu alloy. Tensile properties of two materials show different characteristics at room temperature and high temperature. Al-5.0Cu is better at room temperature and Al-4.7Cu is better at high temperature. The yield strength (YS), ultimate tensile strength (UTS) and elongation in the x direction of Al-5.0Cu at room temperature are 451 ± 10.2 MPa, 486 ± 10.2 MPa and 9 ± 0.5%, respectively. The YS, UTS and elongation in the x direction of Al-4.7Cu at high temperature are 290 ± 4.5 MPa, 356 ± 7.0 MPa and 13% ± 0.2%, respectively.

Originality/value

Experiments show that the increase of Cu element can improve the properties at room temperature of the ZAlCu5MnCdVA alloy by WAAM, but its properties at high temperature decrease.

Details

Rapid Prototyping Journal, vol. 29 no. 4
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 20 June 2023

Kei Kimura, Takeshi Onogi and Fuminobu Ozaki

This work examines the effects of strain rate on the effective yield strength of high-strength steel at elevated temperatures, through tensile coupon tests at various strain…

Abstract

Purpose

This work examines the effects of strain rate on the effective yield strength of high-strength steel at elevated temperatures, through tensile coupon tests at various strain rates, to propose appropriate reduction factors considering the strain rate effect.

Design/methodology/approach

The stress–strain relationships of 385 N/mm2, 440 N/mm2 and 630 N/mm2-class steel plates at elevated temperatures are examined at three strain rate values (0.3%/min, 3.0%/min and 7.5%/min), and the reduction factors for the effective yield strength at elevated temperatures are evaluated from the results. A differential evolution-based optimization is used to produce the reduction-factor curves.

Findings

The strain rate effect enhances with an increase in the standard design value of the yield point. The effective yield strength and standard design value of the yield point exhibit high linearity between 600 and 700 °C. In addition to effectively evaluating the test results, the proposed reduction-factor curves can also help determine the ultimate strength of a steel member at collapse.

Originality/value

The novelty of this study is the quantitative evaluation of the relationship between the standard design value of yield point at ambient temperature and the strain-rate effect at elevated temperatures. It has been observed that the effect of the strain rate at elevated temperatures increases with the increase in the standard design value of the yield point for various steel strength grades.

Details

Journal of Structural Fire Engineering, vol. 15 no. 1
Type: Research Article
ISSN: 2040-2317

Keywords

Article
Publication date: 5 June 2023

Takumi Yamaguchi and Fuminobu Ozaki

The main purpose of this study was to evaluate the tensile strengths of JIS G3549 super high-strength steel strand wire ropes (1,570 MPa-class high-carbon steels) and wire rope…

41

Abstract

Purpose

The main purpose of this study was to evaluate the tensile strengths of JIS G3549 super high-strength steel strand wire ropes (1,570 MPa-class high-carbon steels) and wire rope open swaged socket connections at fire and post fire.

Design/methodology/approach

Steady-state tests from ambient temperature (20 °C) to 800 °C, transient-state tests under the allowable design tensile force and tensile tests in an ambient temperature environment after heating (heating temperatures of 200–800 °C) were conducted.

Findings

The tensile strengths of the wire rope and end-connection specimens at both fire and post fire were obtained. The steel wire rope specimens possessed larger reduction factors than general hot-rolled mild steels (JIS SS400) and high-strength steel bolts (JIS F10T). The end-connection specimens with sufficient socket lengths exhibited ductile fracture of the wire rope part at both fire and post fire; however, those with short socket lengths experienced a pull-out fracture at the socket.

Originality/value

The fundamental and important tensile test results of the super high-strength steel strand wire ropes (1,570 MPa-class high-carbon steels) and wire rope open swaged socket connections were accumulated at fire and post fire, and the fracture modes were clarified. The obtained test results contribute to fire resistance performance-based design of cable steel structures at fire and fire-damage investigations to consider their reusability post fire.

Open Access
Article
Publication date: 25 August 2023

Mohamed Arouri, Adel Ben-Youssef and Cuong Viet Nguyen

In this study, the authors examine the push and pull effects of extreme weather events on migration among governorates in Egypt.

Abstract

Purpose

In this study, the authors examine the push and pull effects of extreme weather events on migration among governorates in Egypt.

Design/methodology/approach

To estimate the effect of extreme weather events on internal migration, the authors use migration gravity models and data from the 1996 and 2006 Population and Housing Censuses. The authors measure weather extremes by the number of months in the past 36 months with temperatures or precipitation of a governorate below the 5th percentile and above the 95th percentile of the distribution of monthly temperatures or precipitation of the corresponding governorate during the period 1900–2006.

Findings

This study’s results suggest that high temperatures in the origin area act as a push factor. High-temperature extremes have a positive effect on out-migration. A 1% increase in the number of months with high-temperature extremes in the original governorate results in a 0.1% increase in the number of out-migrants.

Practical implications

The study suggests that people may respond to weather extremes through migration. However, climate migrants in Egypt may encounter several significant risks that authorities must address.

Originality/value

This study is one of the first attempts to measure the push and pull effect of weather extremes on migration in Egypt.

Details

Journal of Economics and Development, vol. 25 no. 4
Type: Research Article
ISSN: 1859-0020

Keywords

Article
Publication date: 23 October 2023

Francis O. Uzuegbunam, Fynecountry N. Aja and Eziyi O. Ibem

This research aims to investigate the influence of building design on the thermal comfort of occupants of naturally ventilated hospital (NVH) wards to identify the aspects with…

Abstract

Purpose

This research aims to investigate the influence of building design on the thermal comfort of occupants of naturally ventilated hospital (NVH) wards to identify the aspects with the most significant influence on the thermal comfort of hospital buildings during the hot-dry season in the hot-humid tropics of Southeast Nigeria.

Design/methodology/approach

Field measurements, physical observations and a questionnaire survey of 60 occupants of the wards of the Joint Presbyterian Hospital, Uburu in Ebonyi State, Nigeria were undertaken. The data were analysed using Humphreys' neutral temperature formula, descriptive statistics and multiple regression analysis.

Findings

The results revealed that the neutral temperature for the wards ranges from 26.2 °C to 29.9 °C, the thermal condition in the wards was not comfortable because it failed to meet the ASHRAE Standard 55 as only 65% of the occupants said the thermal condition was acceptable. The number and sizes of windows, building orientation, the presence of high-level windows and higher headroom significantly influenced the occupants' thermal comfort vote.

Practical implications

This research is valuable in estimating comfort temperature and identifying aspects that require attention in enhancing the capacity of NVH wards to effectively meet the thermal comfort needs of occupants in the hot-humid tropics of Southeast Nigeria and other regions that share similar climatic conditions.

Originality/value

To the best of the authors’ knowledge, this is the first study of this nature that provides valuable feedback for building design professionals on the performance of existing hospital buildings in meeting users' thermal comfort needs in the hot-dry season of the hot-humid tropics in Southeast Nigeria.

Details

International Journal of Building Pathology and Adaptation, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 2398-4708

Keywords

Article
Publication date: 16 August 2022

Tingneyuc Sekac, Sujoy Kumar Jana and Indrajit Pal

The climate change and related impacts are experienced around the world. There arise different triggering factors to climate change and impact. The purpose of this study is to…

70

Abstract

Purpose

The climate change and related impacts are experienced around the world. There arise different triggering factors to climate change and impact. The purpose of this study is to figure out how changes in vegetation cover may or may not have an impact to climate change. The research will produce ideas for vegetation preservation and replant.

Design/methodology/approach

The investigation was probed for 34 years’ time period starting from the year 1981 to 2015. After testing and checking for serial autocorrelation in the vegetation data series, Mann–Kendal nonparametric statistical evaluation was carried out to investigate vegetation cover trends. Sen’s method was deployed to investigate the magnitude of vegetation cover change in natural differential vegetation index (NDVI) unit per year. Furthermore, the ArcGIS spatial analysis tools were used for the calculation of mean NDVI distribution and also for carrying out the spatial investigation of trends at each specific location within the study region.

Findings

The yearly mean NDVI during the study period was observed to have a decreasing trend. The mean NDVI value ranges between 0.32 and 0.98 NDVI unit, and hence, this means from less or poor vegetated zones to higher or healthier vegetated zones. The mean NDVI value was seen decreasing toward the highlands regions. The NDVI-rainfall correlation was observed to be stronger than the NDVI-temperature correlation. The % area coverage of NDVI-rainfall positive correlation was higher than the negative correlation. The % area coverage of NDVI-temperature negative correlation was higher than the positive correlation within the study region. Rainfall is seen as a highly influencing climatic factor for vegetation growth than the temperature within the study region.

Originality/value

This study in this country is a new approach for climate change monitoring and planning for the survival of the people of Papua New Guinea, especially for the farmer and those who is living in the coastal area.

Details

International Journal of Disaster Resilience in the Built Environment, vol. 15 no. 1
Type: Research Article
ISSN: 1759-5908

Keywords

1 – 10 of over 3000